Closed in 1991, this abandoned pedestrian walkway runs under 6th in Midtown Manhattan between 35th and 40th Streets. It once provided a underground connection between the stations surrounding Penn Station and the stations around Grand Central.

According to a YouTube commenter, the extra long tunnel was dimly lit, unstaffed by the MTA, and was a hotspot for criminal activity.

Appeared to still have its original incandescent lights from 1940, which for a unstaffed passageway of that length made it a haven for crime. The rape of a woman that led to the closure of this and other lightly-used tunnels occurred in March 1991 according to the NYT...and it wasn't even the first one that occurred in there.

In this video from Trainluvr, check out the tunnel just weeks before its close in 1991.